TSSP: List Archives

From: Paul
Date: Sat, 21 Oct 2000 08:01:18 +0100
Subject: Re: [TSSP] New Secondary Voltage Profiling Instrument

I wrote (in another thread)
> ...but short of tapping into the coil...

but I should know by now not to underestimate the determination
of certain experimenters!

Terrell W. Fritz wrote:
> ...  http://63.225.104.49/TeslaCoils/Misc/PaulNich/profiler.jpg

That's a remarkably simple and direct approach, although

> Tiny scratches are made in the secondary at every inch 

not everyone will want to use this method! I think with care
this ought to work quite well. As you say it certainly shouldn't
upset the resonance much. If voltages are quite low you might need
to calibrate away the diode response. I think with this little
device you should be able to get a fairly quick indication of where
on the coil the maximum V gradient is occuring. 

Assuming that the gradient doesn't change that rapidly its 
probably necessary only to sample at a few points along the coil
to get a qualitative check.

Malcolm wrote (in another thread)
> ... I suggest to others that a useful control for any probing
> is to far-monitor the resonator e-field using a small scope
> aerial and look for any change in frequency and/or amplitude
> as a first order check on the perturbance

I think that's quite important, you could also use the base current
as a control reading.
 
> Comments and suggestions are welcome. 

When integrating the differential readings, the random errors
in each reading will tend to average away, but any systematic
error in the readings will tend to add up. Therefore we ought
to consider a top volts monitor, something that could be a
permanent part of the top load, with a small and known capacitance
to it, and with a known calibration. That way we can allow for
its presence as part of the normal top cap, and the final
'integrated' voltage curve could then be normalised to an absolute
reading from the topvolts monitor. It would also provide that
control reading for perturbation check, and it would also enable
transimpedance to be measured.

> As far as I know, this will be the first accurate direct reading
> of a resonating secondary's voltage profile.

First time I've heard of anyone tapping into a coil like this -
except by accident anyway!

> I hope to test it tomorrow and report on the initial results. 

I'm on the edge of my seat waiting for the next installment!

Cheers,
--
Paul Nicholson,
Manchester, UK.
--


Maintainer Paul Nicholson, paul@abelian.demon.co.uk.